Nitrided steel sliding member having improved wear resistance and fatigue strength

Abstract

The steel for nitriding consists of 0.5 to 1.0% of C, 1.0% or less of Si, 0.3 to 1.0% of Mn, 5.0 to 12.0% of Cr, 0.5 to 2.0% of Mo, 0.1 to 0.3% of V, the balance being Fe and exhibits improved wear-resistance and fatigue-strength.

What is claimed is:  
     
       1. Sliding member which consists of a steel consisting of from 0.5 to 1.0% of C, 1.0% or less of Si, from 0.3 to 1.0% of Mn, from 5.0 to 12.0% of Cr, from 0.5 to 2.0% of Mo, from 0.1 to 0.3% of V, the balance being Fe and unavoidable impurities, and a nitriding layer formed on at least the outer peripheral sliding surface of said steel, wherein said nitriding layer comprises crystal grains, compound layer precipitated along the boundaries of the crystal grains, and precipitates consisting essentially of carbonitrides dispersed within the crystal grains and having less than 10 μm in size, and further area percentage of the precipitates from 1 to 10 μm in size is 5% or less. 
     
     
       2. Sliding member according to  claim 1 , wherein the nitriding layer is subsequently not subjected to post-treatment. 
     
     
       3. Sliding member which consists of a steel consisting of from 0.5 to 1.0% of C, 1.0% or less of Si, from 0.3 to 1.0% of Mn, from 5.0 to 12.0% of Cr, from 0.5 to 2.0% of Mo, from 0.1 to 0.3% of V. the balance being Fe and unavoidable impurities, and a nitriding layer formed on at least the outer peripheral sliding surface of said steel, wherein said nitriding layer has a thickness of from 5 to 200 μm and comprises crystal grains, compound layer precipitated along the boundaries of the crystal grains, and precipitates consisting essentially of carbonitrides dispersed within the crystal grains and having less than 10 μm in size, and further area percentage of the precipitates from 1 to 10 μm in size is 5% or less. 
     
     
       4. Sliding member according to  claim 3 , wherein the nitriding layer is subsequently not subjected to post-treatment.